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“Critical Limb Ischemia”: The Need for a New System to Define Disease Burden and Stratify

Amputation Risk and Need for RevascularizationUCSF Vascular Symposium

18 April 2013

Joseph L. Mills, Sr., M.D.Professor of Surgery, Chief, Vascular & Endovascular SurgeryUniversity of Arizona Health Sciences CenterCo-Director, SALSA

No tengo conflictos de interés que revelarI have no conflicts of interest to disclose.

Acknowledgements� Michael S. Conte� David G. Armstrong� Frank B. Pomposelli� Anton N. Sidawy� George Andros� Jack Cronenwett, Pat Geraghty, Rob Hinchliffe, Wayne Johnston, Rick Powell, Andy Schanzer, Spence Taylor

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Rutherford Classification

This patient presented with a severe foot infection and absent pedal pulses. After adequate debridement, and control of infection, angiography and revascularization were performed.

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What is critical limb ischemia and how should it be treated?

“The International Working Group on the Diabetic Foot (IWDGF) thereforeestablished a multidisciplinary working group, including specialists in

vascular surgery, interventional radiology, internal medicine andepidemiology to evaluate the effectiveness of revascularization of the

ulcerated foot in patients with diabetes and PAD. The aim of thismultidisciplinary working group was to produce a systematic review onthe efficacy of (endovascular and surgical) revascularization proceduresand medical therapies in diabetic patients with a foot ulcer and PAD.”

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A systematic review of the effectiveness of revascularization of the ulcerated foot in patients with diabetes and peripheral arterial disease†1. R. J. Hinchliffe1,*, 2. G. Andros2,3. J. Apelqvist3,4. K. Bakker4,5. S. Fiedrichs5, 6. J. Lammer6,7. M. Lepantalo7, 8. J. L. Mills8,9. J. Reekers9,10. C. P. Shearman10, 11. G. Valk11,12. R. E. Zierler12, 13. N. C. Schaper5Article first published online: 23 JAN 2012

Diabetes Metab. Res. Rev., 28: 179–217. doi: 10.1002/dmrr.2249

Medline and Embase search from 1980-2011 performed accordingTo the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Over 11,000 articles were Identified, 865 wereselected as potentially eligible, only 49 could be included in review.Inclusion criteria: diabetes, tissue loss (ulcer or gangrene; no rest pain); Objective documentation of PAD (ABI, TP, angiography)Outcomes: ulcer healing, limb salvage, major amputation, survival

Unanswered Questions?

�What factors determine the risk of amputation once a patient with diabetes gets a foot ulcer?�Does revascularization reduce the risk of major limb amputation in patients with diabetes?�If so, which method of revascularization is most effective and in what settings?

Unanswerable Questions!�These questions are unanswerable due to the lack of an adequate classification system�Vascular classification systems (TASC, Bollinger, and Graziani) focus only on the vascular anatomy, encouraging sub-specialty of “lesionology”�Rutherford and Fontaine classifications are inadequate for the diabetic foot�“Critical Limb Ischemia” is a flawed concept with limited utility and applicability to the diabetic foot

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“Critical Limb Ischemia”� Ischemic rest pain and absolute systolic ankle pressure of less than 40 mm Hg� Ankle pressure < 60 mm Hg systolic in the presence of superficial necrosis of the foot or digital gangrene involving the base of the phalanx� “It was generally agreed that diabetic patients who have a varied clinical picture of neuropathy, ischaemiaand sepsis make a definition even more difficult . . . and these patients should be excluded.”� “Diabetic patients should not be included, or should be clearly defined as a separate category to allow analysis of the results in non-diabetic . . .”

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Hemodynamics and Probability ofHealing of a Diabetic Foot Ulcer

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Diabetic Foot Complications� Diabetes is diagnosed once every 17 seconds!� Up to 70% of the lower extremity amputations in the

world are associated with diabetes

� Every 20 seconds, somewhere in the world, a lower extremity is amputated in a patient with diabetes

�EVERY 20 SECONDS!

Demography is Destiny� Fontaine and Rutherford are pure ischemia models; the concept of CLI was never intended to be applied to diabetics� Global epidemic of diabetes; emerging evidence that etiology of foot ulcers in these patients has changed over the last 2 decades from primarily neuropathic to neuroischemic and purely ischemic� Neuropathy, wound characteristics and infection complicate management� Eurodiale: PAD + infection TRIPLES amputation risk� Our patients have changed but our classification system has not

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Widely used but incomplete classification systems�Wound Depth/Extent�Wagner Grades�PEDIS (1-3 scale)� Texas Wound Classification System� Ischemia�Rutherford 4, 5 and 6�Fontaine 3, 4�Foot Infection: IDSA (1-4 scale)

A Proposal -Lower Extremity Threatened Limb Spectrum

WIFI Index�Wound: extent and depth�Ischemia: perfusion/flow�Foot Infection: presence and extent

Proposed WIFI Index�Based upon existing validated systems or best available data with 4 point scales where �0 = none�1 = mild-moderate�2 = moderate-severe�3 = severe

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Wound – Clinical CategoryGrade Clinical Description

0 Ischemic rest pain; Pre-gangrenous skin change, without frank ulcer or gangrene (Pedis or UT Class 0)

1 Minor tissue loss: small shallow ulceration) < 5 cm2 on foot or distal leg (Pedis or UT Class 1); no exposed bone unless limited to distal phalanx (maximum digital amp x 1-2)

2 Major tissue loss: deeper ulceration(s) with exposed bone, joint or tendon, ulcer 5-10 cm2 not involving calcaneus –(Pedis or UT Classes 2 and 3); gangrenous changes limited to digits. Salvageable with multiple (> 3) digital amps or standard TMA + skin coverage

3 Extensive ulcer/gangrene > 10 cm2 involving forefoot or midfoot; full thickness heel ulcer > 5 cm2 + calcaneal involvement. Salvageable only with complex foot reconstruction, nontraditional TMA (Chopart/Lisfranc); flap coverage or complex wound management needed

Ischemia -Grade ABI Ankle SP TP, TcpO2

0 > 0.80 > 100 mm Hg > 60 mm Hg1 0.60-0.79 70-99 mmHg 40-59 mm Hg

2 0.40-0.59 50-69 mm Hg 30-39 mm Hg

3 < 0.40 < 50 mm Hg < 30 mm Hg

ABI=ankle brachial index; SP= systolic pressure; TP=toe pressureTcPO2=transcutaneous oximetry

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WIFI index is intended to be analogous to the TNM staging system for cancer� A patient with diabetes, a shallow superficial foot ulcer, early cellulitis and an ABI of 0.43 with a TP of 35 mm Hg would be classified as follows:� W-1 I-2 FI-1 or WIFI 121� Utilization of this proposed system would produce a grid of 64 possible combinations of Wound, Ischemia and Infection� Twelve selected limb salvage experts were asked to classify each possible presentation into one of four classes based on two considerations:

Two Distinct Questions�What is the one-year risk of amputation if this limb status were treated with medical therapy alone (i.e., natural history of the condition)?�What is the likelihood the patient would benefit from or require revascularization in order to heal?

Grid Consensus Process�Class I - Very Low�Class 2 - Low�Class 3 - Moderate�Class 4 - High

Risk of Amputation

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Benefit of Revascularization

One-year Amputation Risk By Clinical Stage or Class

58 year old diabetic man; Stage 5 CKD. Ambulatory with contralateral Left BKAPalpable DP pulse, remotely healed Right TMA. R Heel gangrene; no PT pulse

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Fluorescence Imaging to Assess Regional PerfusionIndocyanine green angiography before intervention

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61 y/o diabetic s/p TMA. Palpable DP PulseNon-healing heel ulcer x 15 months; Failed TCC

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Remote left BKA; Ambulatory in prosthesis

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PRE-PTA POST PTA

INDIRECT REVASCULARIZATION

Wound completely healed in 6 weeks

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Conclusions� We won’t be able to assess outcomes and relative efficacy of interventions intended to prevent limb amputation in patients with PAD and diabetes without a uniform classification system� Wound depth, Ischemia, Foot Infection WIFI-Index) are the critical factors that need to be considered and graded, similar to TNM staging for cancer� The WIFI Index is intended to allow assessment, comparison and improvement of outcomes, not to dictate therapy� A simple Risk Comorbidity Index (RCI) and simpler anatomic classification system would be of added value� Alternate measurements of perfusion may also prove useful

www: diabeticfootonline.com

Blog: diabeticfootonline.blogspot.com

http://Twitter.com/jmills1955

For more information:

RCI = Risk Comorbidity Index

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Other comorbidities may be important to consider� “Frailty Markers”� Low HCT (P III study)� Low BMI (BASIL Study)� Severe PAD� Diminished number of measureable ankle pressures and� AP < 50 mm Hg were predictors of decreased survival and AFS in

BASIL� Renal insuffiiciency� Should CKD 4 be included or CKD graded? (BASIL suggests yes;

other studies suggest only dialysis dependence matters) Apelqvist et al. JVS 2011. 53(6):1582-88

Are there better ways to measure foot perfusion?� Ankle-brachial indices� Toe pressures� Toe waveforms� Forefoot PVRs� Transcutaneous oxygen tension� Laser Doppler� Quantitative perfusion using vital dye (ICG)